Piston expander-shell drive-in type



Sept 4 1951 G. J. WOREL. 2,566,591

I PISTON EXPANDER-Sl-IELL DRIVE-IN TYPE Filed April 28. 1949 Patented Sept. 4, 1951 TISTON XPANDEt-SHELL .(Srlei'itl. LWoreL 'Minneapolis, Minna., jassigner #to ".Thexton Manufacturing Gompany, 'Minneafpi olis, Minn,, a :connotation of Minnesota nppl'iestionnprl-es, 1949, seriamente-5 a6 .Claims This invention z-relaite's 'to -expenders for 'the Vskirts vkof pistonsv of internal l. combustion engines, and particularly I to v*an :expander adapted for fpistons having relatively short'wristzpin-bosses, for example, lthose Aused `in the 1 engines produced -by Ford Motor CompanyBniek Division vof-1(ene'ral vMotors Corporationand Dodge Division of fChrys- 1er Corporation;

rWhenthe cylinders 'f 1 internal cornbstion: engines 'become "worn they l'become out-o-round,

'greatlyde'creases theeiciency of the engine.

Piston expanders f-Whieh 'have been `arniliecl Ato 'the interiors 'of the resilient |'piston `rskirts, `vhave been 'used Vvesde'nsively' heretofore. So'me l'have `been of the leaffspring orshell type, wherein the resilient piston expander was interposed beftween 'the 'wristT pin or vthe vWrist -pin lb'osses' and the interior peripheral 'v'alllf the y'piston skirt,

Vexerting-anfouiwvard'pressure 'on' a portion of `the skirt disposed inter'mediately `foi the `Wrist pin bosses. iExamples offsueh"fshellltypefexpanders l are disclosed in m'yUnitedf States LettersPatent No v25355937, granted August '15, YY1944:, fand 2,442,834 grante'dfJiine I8,1'1948.

Shell type expanders of-thisf-genera1type have, 'lfor the most part, been interposed between fthe relatively"elongated wrist pnfbossestand Ythe pis-'- ton skirt, Athe Texp'andeis having legs whose l@extremities bear v'against jthe "wrist pin i bosses. `In such constructions, insertion of the expanderhas been facilitated by spreading therlegs-'withua lpliers 'or other `lvsuitable vtoc/31., thereby v"decreasing the o'v'ei'all height' of the same-'end Y making 'installationeasy.

nWith `'several' typesI "of piston constructionsnow extensively `utilized, the" wrist pin bosses `Vare so short that -'-a'decn'zate-fspreadingefthe legs ofthe expander to faeilitateinse'rtion is impossible;

-In ymy -Pate'nt Nm '2,463,667 granted March 18, 1949, I haver disclosed means whereby -the piston skirt .can be expanded :with a A`structure 'which can f be' qui-eklyf'drivenlinto place from i the lower open-end ofthepiston, and wherein' the expander is in-"engagement-Wththe ends/f the Wrist pin bosses. This expandervis so designedlthat-iti-vvil'l not cause overexpansion of the pistonskirt, and means is Aprovided `yfor "compensating Tor Lexpansion and contraction of" theipiston 'through' wide temperature 'variations y The v'present 'invention Ahas Ias lfan' object Athe provislon'p'ffapiston expanden of the -drive'`in" ,v 2 type vWhich 'can be Jmade *to engage -either the Wrist-'pin-oritsbosses Withthe furtheriprovision of mean-s whereby :the expander is *lirm'ly locked "inf position'and pannotback outof the piston. Another vobject ofthe yinvention is, to provide ajpisco'n expander-onine type-set forthfabove, Whereinthe locking Vrneansis designed l to vfengzaige A the end 'portion of the 'Wrist phi-'abosSJ at f one-oi` 'both sides'Jofithe piston. n Y

A urther'object 'df-ti1e inventionis to `plovi'fflia `'an expander of the""driveiinmtype'with flocking 'means'vvhicn can'be installedwithl approximately `the samefacilityasfonefwithouttheilecking 'fea "ture f The f above and #other otjeets' -a'nd vadveinziges of the invention willniorefully'appearifromlthe following 'description f made in connection with 'the "accompanying drawings, lwherein like 'ref-er- Iencecharactersreferto the same parts through- 20 *out lthe views, "and, =in which: l

Fig. A'l is fa'sectional'4 vi'ew'ftaken 'oni-line l I of Fig. `2, lof rlaj piston "of i:the short Wrist pin boss type, -naving an embodiment -of -my lir'ivention applied thereto Fig. 'Zis'a vertical sectionftakenonfthe line 2-2 of Fig. 1; A

*Fig `v3 'is a `.vertical Lf-seenon taken 'on nthe line v`-3 3 of -E*ig.' -L'the "dotted 2 lines indieatin'g fthe position of the'expander before being drivennto @13136;

Figs4` is a'fperspeetiveiview snowing lanfeinbodi'-v ment of the expander per se, and

' nthe drawingsthereis shown afpiston-`6 'hav-- ingthel usual"'head`-1. "The uppe'rfside-wallf of the piston 'provided 'with fthe lusual -vpiston ring grooves 11a. The head, -finconventional 1fa'shion, lis 'of greater* thieknessvthanthe f depending-skirt `8, 'which iis continuons and inte'giial with fthe head, --and is voutwmdly and foircumierentiany offset soms'ew'havfrorn the inner: peripheryfo'f the head. The-skirt@ in the 'type shown, 1is constructed of resilient, somewhat iiexible Amaterial and "may haive1a`fT-Slot fthel'fm; :This '#Slot eludes fa circumferential :port-,ion 'es Lexten-cling through =the1greatenportienfof 'th'e upper part-of the skirt and intersected *by a -vertical V4`slot 49a, whichv is `disposed i intermediate `of fthe uwrist: ypin bosses 'HL The lewerxpe'rtion ofi the skirt is not Slotted as 1in 4Sofri-e"tl'ie' types AOi." pistons.

The-usual Short fty'pef Wi'ist-pinfbo'ss H1 `iso'f heavy constructienfandis*- mtegrallyffermedwith the inner `v.11.'a.`1ls'-"of the'fskirtS. They-are bored and-:smoothly greundf-'toeaetes bearings iferfthe WriStIJinfI-h My improved expander is adapted to apply pressure and expand the portion of the piston skirt extending about the slots 9 and 9a, intermediately of the wrist pin bosses Ill and at one side of the piston. My expander is equally applicable to slotted or unslotted pistons and is particularly conceived for installation and operation upon apiston' where litle space is lprovided betweenopposing strutsor walls from which the wrist pin bosses protrude.

The structure comprises a relatively wide shell or leaf spring member curved into the general shape of a U in cross section, 'and having rela--v tively wide leg portions I2, which extend in substantially parallel relationship from inwardly folded temperature compensation portions I3.

The article is preferably constructed from comparatively thin spring sheet metal or its equivalent, and after shaping is tempered.

The device is shapedoto form a convex, medial pressure-applying areaA or zone I4 which preferably is the full width of the expander, and is adapted to lie against the inner wall of the piston skirt at an area intermediate'of the wrist pin connections. The two temperature compensation folds I3 are disposed intermediately of the pressure-applying portions l I4. The longitudinal edges of the legs I2, and said folds are opposed and extend parallel with the longitudinal center line of the pressure-applying portion.

Portions of the end edges of the legs I2 are relatively straight as at I2a and in parallel relation to the pressure-applying portion I4. These edges then continue in curved portions I2b which are adapted to conform approximately to the circumierence of the wrist pin II and to be seated against the lower side of thevwrist pin.

Immediately in front of,or Aabove the beginningfof the straight portions I2a are tongues or tooth-like members I2c, formed by cutting slots I2d in the legs I2. It should be noted that these tooth-like members .I2e lie at an angle to the general planes of therlegs I2, being disposed outwardly from the slots I2d, and they also terinmate a short distance above the straight edge portions I2a.

Y, Furthermore, the intermediate portions of the endsof the legs I2. are provided with recesses I2e of arcuate shape which are adapted to conform to the shape of the wrist pin bosses I and to be seated against the lower side of the wrist pin bosses.

The offset orrrecessed portions I2e nicely iit the extremities of the wrist pin bosses ID, whereby, when the expander is sprung into place, they will seat snugly against the bosses. At the same time the tooth-like members I2e will expand or spring away from eachother and their relatively sharp corners and edges will bite into the metal of the wrist pin bosses and firmly anchor the expander against Aaccidental displacement. The curved portions I2b prevent the expander from being driven too far into the piston and the tooth-like elementsIZc keep5the expander from backing out. Thus it will be seen that while the device is relativelyA easy to install, it will automatically lock itself into position.

In installation, the legs I2vare sprung slightly towards each other andthe expander is inserted upwardly from the dotted line position of Fig. 3. The, inclined portions I2a of the legs contact the wristV pin withra wedging action, and as the expander is driven into position, it will flex as shown inv Fig. 5 dotted lines. When in position, the wrist pin bosses will seat intheq recesses I2e and the tooth-like members I2e will expand into their locking positions described above.

In the insertion of the expander, the skirt is not subjected to any undue expansion beyond that desired by reason of the tapering of the legs at I2a and also due to the fact that the legs of the device are flexed inwardly through the provision of the intermediatefolds I 3;v When the recessed portions'slip intoposition relative to the bosses of the piston, the material which forms said recesses furnish thrust applying seats so that undue wear is not placed on the wrist pins by reason of the engagement of the edges of the legs with the wrist pin. In other words, when seated,

not only do the extreme edges of the expander legs engage the wrist pin, but a base of resistance is provided by the extremities of the wrist pin bosses I Il through the engagement of the arcuate, shouldered recesses I2e of the legs.

The opposed, inwardly extending intermediate folds I34 in vmy expander .provide an efficient means for insuring properiunctioning of the expander regardless of expansion and contraction of the piston parts due to wide temperature variations during the operation of the engine. The wallsand wrist pinbosses of the piston are usually `constructed from alloys having a co-eflicient of expansion considerably greater thanspring steel from which the expander is constructed. Thus, unless provision is made for compensationfor such expansion during the range of temperatures present in normal internalcombustion engines from starting point to operation at high speed,

considerably greater pressure on the piston skirt would be applied when the temperature is materially raised. This compensation is made through the intermediate folds I 3. They are so constructed that substantially the samepressure is applied to the piston skirt with these variations of temperature. .Y .l

The important andabouttheonly difference between the devices ,disclosed herein and in the above mentioned Patent No.,2,463,667, is the provision herein of the lock-ing means in the form of the tooth-like elements I 2c.r Ihe vexpander functions ,in Ythe sameniannen but the present constructionprovides'a positive lock in addition to the securing function secured with the side walls of therecesses, I2e. Y

It will, of course, be understood `that various changes may be. made in the form, details, arrangement and proportions of the various parts without departing `:from thescope of my invention.' f v v What I claim is; Y Y ,Y

Y l. A piston expander for an-,internal `combustion engine pistonof Vthe typehaving opposed, substantially cylindrical wrist pin bosses, a cylindrical wristvprl iournaled therein andan annular, dependingrpiston skirt. of resilient vmaterial comprising; a generally; U -sha pe d resilient body having legs of considerable width, said legs having indentedy portions shaped to fit at least partially about the wrist pinbosses, and nat least one of said legs having its upper'end portiony split to form a tooth-like member,4 said tooth-like membervbeing bent laterally and adapted t0 engage the wrist pin boss in cooperation with the adjacent indented portion of saidleg to positively prevent ldisplacement of the expander. v H A 2. A piston expander for an internal combustion engine piston of the type having opposed, substantially cylindrical wrist Ypin bosses, a cylindrical wrist pin vjournaled therein and an an` miler, .depending pieten, ekirt ef resilient meteiel comprising; a resilient body having a pair of legs and a connecting portion, said legs having portions oiset from their general planes and providing' wrist pin boss-receiving bights and at least one of said legs having an inwardly extending slot formed in one of its end portions and having a part thereof adjacent said slot bent laterally to positively engage the adjacent wrist pin boss whereby displacement of the expander in at least one direction may be positively precluded.

3. The structure in claim 2, and said laterally bent part being resiliently shiftable relative to the leg by which it is carried.

4. A piston expander for an internal combustion engine piston of the type having opposed, substantially cylindrical wrist pin bosses, a cylindricall wrist pin journaled therein and an annular, depending piston skirt of resilient material comprising; a resilient body having a pair of legs and a connecting portion, said legs having outer end portions shaped to fit partially about the wrist pin bosses, said connecting portion being located to apply pressure against the resilient skirt of a piston, and at least one of said legs having a slotted end portion a part of which extends laterally, said laterally extending part be ing adapted to positively engage the adjacent wrist pin boss and to cooperate with the adjacent boss tting end portion to positively prevent longitudinal movement of the expander relative to the skirt.

5. A piston expander for an internal combustion engine piston of the type having opposed, substantially cylindrical Wrist pin bosses, a cylindrical wrist pin journaled therein and an annular, depending piston skirt of resilient material comprising; a generally U-shaped resilient body having legs of considerable width, said legs having indented portions shaped to fit at least partially about the wrist pin bosses, and at least one of said legs having one of its end portions slotted and having at least a part of said slotted end portion bent laterally to positively engage the adjacent boss to prevent movement of the expander relative to the skirt in at least one direction.

6. A piston expander for an internal combustion engine piston of the type having opposed, substantially cylindrical wrist pin bosses, a cylindrical Wrist pin journaled therein and an annular, depending piston skirt of resilient material comprising; a generally U-shaped resilient body having legs of considerable width, at least one of said legs having a surface adapted to register with the adjacent wrist pin boss when the expander is positioned for operation to prevent movement of the expander in one direction and at least one of said legs having one of its end portions slotted and having at least a part of said slotted end portion bent laterally to positively engage the adjacent boss whereby movement of the expander relative to the skirt in the opposite direction may be prevented.

GLEN J. WOREL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,958,154 Six May 8, 1934 2,034,005 Six Mar. 17, 1936 2,119,137 Moore May 31, 1938 2,286,858 Knoebel June 16, 1942 2,333,893 Six Aug. 28, 1945 

